diff --git a/src/requirements.txt b/src/requirements.txt
index b49f80a..eee6132 100644
--- a/src/requirements.txt
+++ b/src/requirements.txt
@@ -9,3 +9,4 @@ pytest-cov>=2.5, <3.0
 pytest-mock>=1.7.1,<2.0
 pytest>=3.4, <4.0
 wheel==0.32.2
+flake8